Technical Field
This application relates to a method and an article of manufacture for determining a rate of change of orientation of a plurality of fibers disposed in a fluid.
When a fiber-reinforced plastic is injected in a mold cavity utilizing an injection molding process, a flow of the plastic in the mold cavity orients the fibers. The resulting fiber orientation pattern determines many properties of the molded part, including stiffness, strength, thermal expansion, warpage, and shrinkage.
A mathematic model has been developed that attempts to predict a rate of change of orientation of fibers during injection of plastic into a mold cavity. A problem with the model is that the predicted rate of change of orientation of the fibers has significant deficiencies, particularly in parts with relatively short flow lengths and relatively fast filling speeds. In particular, the predicted rate of change of orientation of the fibers is greater than an observed rate of change or orientation of the fibers.
Accordingly, the inventors herein have recognized a need for an improved method for determining a rate of change of orientation of fibers in a fluid.